Among conventional fabrication processes for thin film transistor liquid crystal displays (TFT-LCDs), Advanced Super Dimension Switch (AD-SDS, also abbreviated as ADS) generates a multi-dimensional electric field with both an electric field produced at edges of slit electrodes in the same plane and an electric field produced between a slit electrode layer and a plate-like electrode layer, consequently, liquid crystal molecules at all orientations, which are located directly above the electrodes and between the slit electrodes in a liquid crystal cell, can be rotated, thereby enhancing the work efficiency of liquid crystals and increasing the light transmittance. Therefore, the ADS technology can improve the picture quality of TFT-LCDs and has advantages of high transmittance, wide viewing angle, high aperture ratio, low chromatic aberration, low response time and being free of push Mura, etc.
FIG. 1 illustrates a schematic configuration of an array substrate in conventional ADS-mode LCDs, in which films are formed in the following order: a gate line P1, a semiconductor layer P2, a transparent pixel electrode P3, a first data line P4 and a first transparent common electrode P6, where the first transparent common electrode P6 is disposed over the transparent pixel electrode P3 and an electric field is formed between the first transparent common electrode P6 and the transparent pixel electrode P3. The first transparent common electrode P6 is a slit electrode and the transparent pixel electrode P3 is a flat or plate-shape electrode or a slit electrode. Herein, the term “over” is used to indicate position relationship and does not necessarily represent contact with each other. FIG. 2 illustrates a cross section taken along the line A-B of FIG. 1. As shown in FIG. 2, neither the transparent pixel electrode P3 and a part of the first data line P4 connected thereto is exposed, on the contrary, they are covered by an insulating layer P7. As a result, the switch property of the TFT can not be tested.
A signal voltage of the transparent pixel electrode can not be obtained due to that the transparent pixel electrode is not exposed on the top layer, which makes it impossible to test the switch characteristic of the TFT in the pixel element and causes severe difficulty in test and analysis.